Nebulizers are devices used to introduce fine droplets of liquid into a flowing stream of air that is to be inhaled. Nebulizers are usually used to medicate a patient's lungs.
Among other things, an effective nebulizer must produce droplets of liquid of the right size. If the liquid droplets are too big they plate out on equipment or even in the trachea or bronchial tubes of the patient and as a result insufficient medication reaches the patient's lungs. On the other hand, if the droplets are too small they do not deposit in a patients lungs and are exhaled, and the patient does not receive sufficient medication.
Most nebulizers are connected in series with a device to supply pressurized air to the patient and the nebulizers have a reservoir or sump to contain the liquid medication. If a patient is to be given a measured amount of liquid medication it is necessary for the nebulizer to function so that all of the liquid medication is drained from the reservoir. Otherwise the unused amount must be accounted for. A device having most of the above-noted characteristics is described in U.S. Pat. No. 3,762,409. In the nebulizer described in that patent draining of the reservoir of liquid is accomplished by making the reservoir acorn-shaped so that as the liquid is consumed it is drained toward the converging bottom point of the acorn where the liquid inlet to the nebulizer system is located. With that arrangement substantially all of the liquid medication is introduced into the air supply to the patient if the nebulizer is kept vertical.
In order to minimize the amount of medication that plates out on the walls of the equipment it is important that the nebulizer be located close to the mouthpiece through which a patient inhales medicated air. When a patient using a nebulizer changes position the nebulizer will move from a completely vertical orientation and as a result some breaths of air are not medicated. Also, frequently, the last few drops of liquid medication are not introduced into the inhaled airstream and less than the full dose of medication is provided to the patient.